Dispensers that are designed for dispensing animal feed and other loose, pourable granular material may comprise a hopper or other container for retaining a supply of feed and an outlet for dispensing feed from the hopper in a controlled fashion. Such systems have widespread use in many areas—for example in animal husbandry such systems are useful for releasing feed in a controlled fashion into a feed trough via gravity. One such system maintains a constant supply of feed in the trough wherein the feed that is removed by an animal is constantly replaced from the hopper. Examples of such systems are described in U.S. Pat. No. 6,923,142 and the references cited in said patent. Such systems permit a relatively large amount of feed to be stored in the hopper, where it can be located above the ground surface and can be protected against moisture, vermin and other adverse conditions. The system allows for on-demand feeding by maintaining a relatively small amount of feed available to the animal at all times.
In such systems, it is desirable to provide a means to accommodate different types of feed having, for example, different particle sizes or other physical characteristics. An on-demand feeder of the type described above typically comprises a hopper or other bulk storage container with a slot or other opening at its base to dispense contents by gravity flow. The feed is deposited onto the surface of a shelf or trough located below the opening which is exposed for access by the animal. The feed piles up in a mound on the exposed feed surface where it can be accessed by the animal. The mound continues to grow as feed is released from the outlet until the top of the mound reaches the outlet, which blocks further feed from being discharged. As feed is removed from the feed surface, for example as it is consumed by an animal, the mound lowers which then permits additional feed to be released from the outlet. In this fashion, the system is maintained in a steady state wherein feed that is removed from the surface is automatically replenished until the hopper is empty.
In systems of this type, the spacing between the feed surface and the hopper outlet can be a key factor in the efficacy of the system. If this spacing is too great, the mound will become too large for the trough or shelf to hold and will overflow the feed surface before the top of the mound reaches the hopper outlet, with the result that the hopper will be quickly emptied as the feed spills off the surface. If the spacing is too small, then the outlet will be blocked without forming a sufficient mound on the surface; feed will be unable to exit the outlet and/or the animal will be unable to access the feed on the surface. It will be seen that the appropriate spacing depends on several factors including physical characteristics of the feed, which determines the angle of repose of the mounded feed and the configuration of the underlying surface which determines the size of the mound that can be deposited thereon.
Means have been disclosed in the prior art relating to gravity feed systems of the type described above to permit adjustment of the spacing between the hopper outlet and the underlying shelf. U.S. Pat. No. 6,923,142 describes a system having a floating shelf suspended from straps that can be raised or lowered to adjust this spacing. The straps are each engaged to a rotatable plate wherein raising or lowering of these straps is accomplished by rotating the plate such that rotational movement of the plate is translated into vertical movement of the strap. When the shelf is placed in its desired position, the rotatable plate is locked against further rotation by engaging a toothed portion of the plate with a static component that has complementary teeth. This arrangement results in the spacing between the hopper outlet and the shelf to be adjusted in discrete increments proportional to the configuration of the mating teeth.
Systems disclosed in the prior art suffer from several drawbacks. One such drawback is that in order to adjust the shelf spacing, the mating teeth of the adjustment member must be disengaged, which causes the full weight of the feed-bearing shelf to be borne by the operator until the teeth can be re-engaged in the new position. This makes adjustment difficult, especially for one-handed operation. As a result of this and other drawbacks, there is a need for an improved animal feed dispenser in which the spacing between the container outlet and the underlying shelf can be controlled in a highly adjustable fashion that is easy to use while minimizing the risk of slippage.